The present invention relates to a storage system and a data storage method. This invention is suited for use in a storage system using a storage apparatus provided with an AOU (Allocation On Use) function.
With the recent development of the information-oriented society, storage apparatuses providing a host apparatus with data storage areas have been receiving an increasing amount of data to be stored, and storage apparatus capacity has been expanded.
In order to expand storage capacity, this kind of storage apparatus generates a disk array configured based on RAID (Redundant Array of Independent Disks) from several physical disks, and collects a plurality of so generated physical storage resources to make a physical volume. Then, a storage area of a capacity requested by a host apparatus is taken out from the storage area provided by the so generated physical volumes to make a logical volume.
In connection with the above, technology called AOU function has been proposed where, instead of making a logical volume of a fixed capacity from physical volumes, a host apparatus is initially provided with a virtualized logical volume, and, in response to requests from the host apparatus, a dynamically variable storage area is allocated from within the storage area provided by the physical volumes (see JP Patent Publication No. 2003-015915 and others). This AOU technology can realize the dynamic capacity expansion of a virtualized logical volume.
Meanwhile, technology called copy function has also been disclosed where data stored in an area in a storage apparatus is replicated in another storage area within the same storage apparatus, or in another external storage apparatus (see JP Patent Publication No. 2005-328729 and others). With this copy function, if data stored in one area is lost, it is possible to utilize the same data stored in another area.